C++ API¶

The C++ API of bob.io.image allows users to read and write images in different file formats. For all image tyres, there exist two functions for reading and writing image, a function to peek the color information (if applicable) and a C++ class that can be used for more detailed information about the image.

Generic functions¶

These functions read and write images based on the filename extension. Currently, only uint8_t data type is supported (because this data type is supported by all of our codes). For other data types, please use the specialized functions as described below.

bool bob::io::image::is_color_image(const std::string &filename)¶: Returns true if the image with the given name is a color image, else false. It might raise an exception if the extension is not supported.

blitz::Array<uint8_t, 2> bob::io::image::read_gray_image(const std::string &filename)¶: Reads a gray image. It might raise an exception if the extension is not supported.

blitz::Array<uint8_t, 3> bob::io::image::read_color_image(const std::string &filename)¶: Reads a color image. It might raise an exception if the extension is not supported.

void bob::io::image::write_gray_image(const blitz::Array<uint8_t, 2> &image, const std::string &filename)¶: Writes the gray image. If the file exists, it will be overwritten.

void bob::io::image::write_color_image(const blitz::Array<uint8_t, 3> &image, const std::string &filename)¶: Writes the color image. If the file exists, it will be overwritten.

BMP¶

blitz::Array<uint8_t, 3> bob::io::image::read_bmp(const std::string &filename)¶: Reads a color BMP image of data type uint8_t.

void bob::io::image::write_bmp(const blitz::Array<uint8_t, 3> &image, const std::string &filename)¶: Writes the BMP color image . If the file exists, it will be overwritten. Only uint8_t data type is supported.

GIF¶

blitz::Array<uint8_t, 3> bob::io::image::read_gif(const std::string &filename)¶: Reads a color GIF image of data type uint8_t.

void bob::io::image::write_gif(const blitz::Array<uint8_t, 3> &image, const std::string &filename)¶: Writes the GIF color image . If the file exists, it will be overwritten. Only uint8_t data type is supported.

JPEG¶

bool bob::io::image::is_color_jpeg(const std::string &filename)¶: Returns true if the JPEG image with the given name is a color image, else false.

template<int N>
blitz::Array<uint8_t, N> bob::io::image::read_jpeg(const std::string &filename)¶: Reads a JPEG image of the given type (grayscale: N=2 or color: N=3). Only uint8_t data type is supported. Please assure that you read images of the correct color type, see bob::io::image::is_color_jpeg().

template<int N>
void bob::io::image::write_jpeg(const blitz::Array<uint8_t, N> &image, const std::string &filename)¶: Writes the JPEG image of the given type (grayscale: N=2 or color: N=3) to a file with the given filename. If the file exists, it will be overwritten. Only uint8_t data type is supported.

TIFF¶

bool bob::io::image::is_color_tiff(const std::string &filename)¶: Returns true if the TIFF image with the given name is a color image, else false.

template<class T, int N>
blitz::Array<T, N> bob::io::image::read_tiff(const std::string &filename)¶: Reads a TIFF image of the given type (grayscale: N=2 or color: N=3). Only uint8_t and uint16_t data types are supported. Please assure that you read images of the correct color type, see bob::io::image::is_color_tiff().

template<class T, int N>
void bob::io::image::write_tiff(const blitz::Array<T, N> &image, const std::string &filename)¶: Writes the TIFF image of the given type (grayscale: N=2 or color: N=3) to a file with the given filename. If the file exists, it will be overwritten. Only uint8_t and uint16_t data types are supported.

PNG¶

bool bob::io::image::is_color_png(const std::string &filename)¶: Returns true if the PNG image with the given name is a color image, else false.

template<class T, int N>
blitz::Array<T, N> bob::io::image::read_png(const std::string &filename)¶: Reads a PNG image of the given type (grayscale: N=2 or color: N=3). Only uint8_t and uint16_t data types are supported. Please assure that you read images of the correct color type, see bob::io::image::is_color_png().

template<class T, int N>
void bob::io::image::write_png(const blitz::Array<T, N> &image, const std::string &filename)¶: Writes the PNG image of the given type (grayscale: N=2 or color: N=3) to a file with the given filename. If the file exists, it will be overwritten. Only uint8_t and uint16_t data types are supported.

NetPBM¶

Note

Internally, the image IO is based on the filename extension to decide, which codec to use. Hence, the filename extension needs to match the function and data type that you use. Use .pbm for binary, .pgm for gray level images, and any other extension (typically .ppm) for color images.

bool bob::io::image::is_color_p_m(const std::string &filename)¶: Returns true if the image with the given name is a color image, else false.

template<class T, int N>
blitz::Array<T, N> bob::io::image::read_p_m(const std::string &filename)¶: Reads an image of the given type (grayscale: N=2 or color: N=3). Only uint8_t and uint16_t data types are supported. Please assure that you read images of the correct color type, see bob::io::image::is_color_p_m().

template<class T, int N>
void bob::io::image::write_p_m(const blitz::Array<T, N> &image, const std::string &filename)¶: Writes the image of the given type (grayscale: N=2 or color: N=3) to a file with the given filename. If the file exists, it will be overwritten. Only uint8_t and uint16_t data types are supported.

template<class T>
blitz::Array<T, 2> bob::io::image::read_pbm(const std::string &filename)¶: Reads an binary image. Only uint8_t and uint16_t data types are supported. Filename extension .pbm is required.

template<class T>
void bob::io::image::write_pbm(const blitz::Array<T, 2> &image, const std::string &filename)¶: Writes the binary image to a file with the given filename. If the file exists, it will be overwritten. Only uint8_t and uint16_t data types are supported. Filename extension .pbm is required.

template<class T>
blitz::Array<T, 2> bob::io::image::read_pgm(const std::string &filename)¶: Reads an grayscale image. Only uint8_ and uint16_ data types are supported. Filename extension .pgm is required.

template<class T>
void bob::io::image::write_pgm(const blitz::Array<T, 2> &image, const std::string &filename)¶: Writes the grayscale image to a file with the given filename. If the file exists, it will be overwritten. Only uint8_t and uint16_t data types are supported. Filename extension .pgm is required.

template<class T>
blitz::Array<T, 3> bob::io::image::read_ppm(const std::string &filename)¶: Reads an binary color image. Only uint8_ and uint16_ data types are supported. Filename extension cannot be .pbm or .pgm.

template<class T>
void bob::io::image::write_ppm(const blitz::Array<T, 3> &image, const std::string &filename)¶: Writes the color image to a file with the given filename. If the file exists, it will be overwritten. Only uint8_t and uint16_t data types are supported. Filename extension cannot be .pbm or .pgm.